The turbulence characteristics in a tube with a self-rotating cleaning plastic twisted tape insert are investigated experimentally by using a 2D frequency shifting Laser Doppler Velocimeter (LDV) System. The results show that the behavior of fluid flow in a tube with a self-rotating cleaning twisted tape insert is different from that in a smooth tube. The twisted-tape makes flow field change ultimately. The fluid flow in the tube with a self-rotating cleaning plastic twisted-tape insert is a spiral motion following the self-rotating twisted tape. The axial velocity is higher in the annular area near the tube wall than that in the central area of the tube, and it increase by 25% or so. The axial turbulence intensity is larger than that in the smooth tube, and it increase by 68% or so. The fluid flow has an obvious tangential motion, the tangential velocity increases as the radius; the tangential turbulence intensity is also large, and it is higher 10 times than the axial turbulence intensity. The turbulent characteristics of fluid flow in the tube with a self-rotating cleaning twisted tape insert will help to study the mechanism of heat transfer enhancement.
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